Broadcasting system



March 9, 1943. J. F. BYRNE 2,313,048

BROADCASTING SYSTEM Filed June 23, 1938 S Sheets-Sheet 1 T"; l a N 13%.. l b

5/05 BAA/0 f F/FLD //Vr/1/5/7} Ly! 0 W I J. I l f? owe/5, 1 7620 /A 7/vs/7r J 2 a OSCILLATOR v CARRIER- PHASE AND AMPLIFIER ADJUSTING AMPLIFIER NETWORK AUDIO PHASE SH'FT SSJJLTTZZ ZLZ'FSTZR NETWORK QZ BALANCED LINEAR M T AMPLIFI- NETWORK ER INVENTOR.

' Q PROGRAM 1 LINE G ATTORNEY. 7

March9, 1943. J. F. BYRNE 2,313,043

BROADCASTING SYSTEM Filed June 23, 1938 5 Sheets-Sheet 2 INVENTOR. 3012; 6%,

March 9, 1943. J. F. BYRNE 2,313,043

BROADCASTING SYSTEM Filed June 23, less 5 Sheets-Sheet z- S INVENTOR.

BY 6 A.7TORNEY March 9, 1943,

J. F. BYRNE 2,313,04

BROADCASTING SYSTEM 5 Sheets-Sheet 5 Filed June 25, 1938 INVENTOR.

I. TORNEY Patented Mar. 9, 1943 BROADCASTING SYSTEM John F. Byrne, Cedar Rapids, Iowa, assignor to Collins Radio Company, Cedar Rapids, Iowa, a

corporation of Iowa Application June 23, 1938, Serial No. 215,465

26 Claims.

My invention relates broadly to high frequency signal transmission systems and more particularly to a transmitting system in which the total power output of the system is substantially constant throughout the cycle of modulation.

One of the most important objects of my invention is to provide a means for signalling, using amplitude modulated waves in which the efficiency of power conversion is exceptionally high.

Another object of my invention is to provide a system of signalling by means of amplitude modulated waves in which the vacuum tube utili zation is of a high degree. For example, in the system to be described, the peak power output is one and one-half times. the carrier power of the transmitter as contrasted with conventional systems where the peak power output is necessarily four times the carrier power of the transmitter.

Still another object of my invention is. to provide a system of radio transmission in which the percent amplitude modulation is the same in all directions, but in which the phase of the modulation varies in a prescribed manner; that is, the phase angle is an integral multiple of the space angle in the ground plane.

A further object of my invention is to provide a means for transmission of double side band signal components to produce amplitude modulation of a transmitted carrier using a system in which the mutual coupling of the carrier transmitter and the side band transmitter is zero.

A still further object of my invention is to pro vide a means for the transmission of double side band signal components which are the result of modulation using N phase audio frequency current, from N transmitters and antenna systems which are 50 arranged that the mutual coupling of the N transmitting systems is zero.

Another object of my invention is to provide a system of radio transmission wherein the rootrnean-square radio frequency power output is :onstant throughout the modulation cycle.

Still another object of my invention is to prozide a polyphase radio broadcasting system vherein the radio frequency carrier energy is ungle phase and modulated by polyphase signal :nergy coordinated with spacial sectors in ac- :ordance with the number of phases of the moduation energy.

A further object of my invention is to provide system of radio transmission of double side band ignal components wherein carrier and side band omponent are separately generated and comantenna systems, the side band components being polyphase in character and cooperable, and the carrier component single phase for obtaining high efliciency in transmission.

A still further object of my invention is to provide a system of radio transmission including the propagation of an unmodulated carrier wave and the modulation thereof in space by the addition of side band components separately generated and propagated and of polyphase character to obtain broadcast coverage.

Another object of my invention is to provide a polyphase radio broadcasting system wherein the phase of an amplitude modulation is a function of the azimuth angle while the carrier energy is independent, of such modulation.

Other and further objects of my invention reside in the combination and arrangement of apparatus and the operation thereof as hereinafter set forth more particularly with reference to the accompanying drawings in which:

Figures 1a and 1b are theoretical and diagrammatic showings, respectively of a fundamental radiating arrangement illustrative of the basic ined in space by radiation from coordinated 55 features of my invention; Fig. 2 is a diagram of the arrangement of antennas in a simple polyphase broadcasting system in accordance. with my invention; Figs. 3a, b, c and d are special diagrams of the magnitude of the field intensities in different phases of the modulation cycle, the relation to the azimuth angle being apparent; Fig. 4 is a block diagram of the system of my invention; Fig. 5 is a schematic diagram of a transmitter for supplying energy of the proper character to the antennas in accordance with the system of my invention; Fig. 6 is a graph showmg calculated performance data relative to the audio phase shifting networks shown in Figs, 4 and 5; and Fig. 7 is a schematic diagram showing a modified form of antenna arrangement and one manner of coupling the same to the transmitter shown in Fig. 5.

In the conventional system of amplitude modulation, the final amplifier tubes must be of suflicient rating to supply peak power equal to four times carrier power of the transmitter. In the system to be described, the maximum power output of the transmitter is equal to one and onehalf times the carrier power and the final amplifier tubes have a maximum capability which is two times the carrier power. Under any condition of sustained modulation, the power output of the transmitter is constant throughout the audio cycle. This latter feature i of particular importance, as it results not only in high efiiciency, but in a tube economy of considerable magnitude in high power transmitters.

The polyphase nature of the system is the result of using directional radiating elements to produce an essentially rotating modulation field in which, at a particular instant, modulation peaks occur in the north direction, carrier values occur to the east, modulation minima to the south, carrier values to the West. One quarter of the modulation cycle later, modulation peaks occur to the east, carrier value to the south, minima to the west, and carrier values to the north. As the modulation progresses through the cycle, the peaks of modulation rotate about the transmitting system at the modulating frequency.

In the discussion of the various features of the system of broadcasting covered in this invention, attention will be entirely directed to what might be termed a two-pole four-phase system. By carrying out certain generalizations, one can easily arrive at a system described as an n-pole N-phase case.

Inasmuch as the system to be described is one in which modulation is a function of the azimuth angle, several simple systems will be reviewed, which will readily lead up to the polyphase system of my invention.

A system in which the percent modulation is a function of the azimuth angle The most commonplace of these systems is the ordinary radio range beacon used in this country. In the newer of these systems, carrier energy is supplied to a nondirectional radiator, indicated at o in the diagram Fig. la, and a single frequency single side band current is supplied to a figure-H! directional system consisting of the r d cos @(i --g) S111 w( cos t A system in which the phase of a modulation of the pure amplitude type is a function of the azimuth angle Consider the system of three antennas as before and, with reference to Fig. 11), let the following currents be established in them:

in: I0 005 wll i1: I1 sin wt cos pt i1: I1 sin wt cos t Where I w/21r is the carrier frequency p/2Tr is the modulation frequency I0 is the maximum value of current in the carrier antenna I1 is the maximum value of current in the side band antenna The field intensities due to these radiators (assumed identical) at a distance 10, where T0 is-at least ten wavelengths, may be written:

Where The sum e1+e1' becomes d cos 0 cos t two antennas, i and I of Fig. la. Thes an- Now, if cod/C, the spacing in electrical degrees.

tennas are placed in the same straight line with radiator o and with equal spacing. If we imagine the antennas to be placed in a north and south line, and we measure an angle 6 clockwise from is less than 30,

ad ad sin cos 0= cos 0, very nearly.

north, the ratio of the side band field intensity Hence to the carrier field intensity will be proportional to the absolute value of the cosine of this azimuth angle. In the conventional beacon system the antennas of Fig. 1a are supplemented by two more antennas placed in line with the carrier antenna and at right angles to the first directional pair. These antennas produce a figure-of-B pattern at right angles to the first pair and the modulation thus produced is proportional to the absolute valueof the sine of the azimuth angle. The on-course indication is given when the percent modulation is the same for both directional pairs. It should be pointed out that the resulting signal is one consisting of carrier and a single side band, and would not be suitable for conventional broadcast transmission using conventional receivers.

The complete field is T To cos 0 cos pt] (1) The factor The antenna currents are:

io=Io 005 mi 21:11 sin wt cos pt 'il'E I1 sin wt cos t =I1-sin of sin t iz'z'Ir sin wt sin pi The field intensities become r Zoos sin w(t cos t e sin w i sin t Tl C which becomes E total R.nrs=- [i+% cos r-a] 2 This Equation 2 shows that the audio phase is dependent upon the azimuth angle. the modulation factor is independent of the azimuth angle, and only depends upon the relative magnitudes of I1 and I0.

Figures 3a, 3b, 3c and 3d are a pictorial representation of Equation 2 and the vectors show the magnitude of the field intensities in the different directions noted as the modulation cycle progresses. I

The transmitting equipment used to generate the currents in, i1, and i2 is shown in the schematic diagram of Fig. 4. Fig. is a wiring diagram of a transmitter embodying the form of my invention shown schematically in Fig. 4.

In Fig. 4, element I is a source of carrier frequency energy consisting of the conventional master oscillator and radio frequency amplifier Used to provide radio frequency excitation to the following amplifier stages. Element 2 is a radio frequency power amplifier supplying the carrier frequency energy transmitted to the central radiator, 4, of the antenna system, through radio frequency phase adjusting network 3, which provides the proper phase relation between the carrier current in antenna 4 and the side band currents in antennas 9 and lil. Elements 5 and 6 are balanced modulators supplied with carrier Further,

frequency excitation from source I and audio modulation frequencies from networks II and I2. The audio components applied to balanced modulators 5 and 6 are substantially electrical degrees out of phase with respect to each other by reason of the difference in delay of the two audio frequency phase-shifting networks II and 2, both of which are connected to the same source of audio frequency current, program line 13. Balanced modulators 5 and 6 generate side band frequencies corresponding to the sum and difference of the carrier frequency and the audio modulation frequencies, but suppress the original carrier frequency. These double side band components are amplified by linear amplifiers and 3 to the power level required in the two side band antenna systems consisting respectively of antennas 9 and I0.

io=Io cos of (3) i1=I1 (sin wt) cos t) (4) i2=I1 (sin wt (sin t) (5) (cos 0 cos t-l-sin 0 sin 0} Equation 3 shows the carrier current in antenna 4 as a function of only the carrier frequency w. Side band currents i1 and i2 in Equations 4 and 5 have the factor cos of replaced by sin wt, indicating a 90 degree phase difference between the carrier current in and the suppressed carrier current in antennas 9 and Ill. The factors cos i and sin t in Equations 4 and 5 indicate balanced modulation by audio frequency currents which are 90 degrees different in phase for balanced modulators 5 and 6.

In the wiring diagram of the transmitter shown in Fig. 5, the portions of the circuit enclosed by dotted lines and labeled 1 to 13 inelusive represent the corresponding elements of Fig. 4. In the oscillator-amplifier element I, V1 is a conventional crystal controlled oscillator tube, and V2 a radio frequency amplifier tube. A1 and A2 represent the filament current sources of V1 and V2 respectively, B1 is the plate current source of V1 and B2 that of V2. G1 is a source of negative D.-C. grid bias, and B3 is a source of positive screen potential, for amplifier V2. Condensers C1 to C5 are D.-C. blocking condensers. H1, H2, and H3 are radio frequency choke coils. R1 is the grid leak resistor for oscillator tube V1, and K is a piezo-electric crysta} for determining the frequency of oscillation. The tuned circuit consisting of condenser C6 and coil L1 supplies carrier frequency excitation from the oscillator circuit to the grid of the amplifier circuit through blocking condenser C3. The amplifier tuned circuit consisting of condenser C7 and coil L2 supplies radio frequency excitation to the carrier amplifier in element 2 and the balanced modulator tubes in elements and 6.

The element 2, V3, is a carrier power amplifier tube of sufficient power to amplify the carrier energy to the power level required in antenna 4. A3 is the filament current source for V3, and G2 and B4 are the grid bias and plate voltage sources, respectively. Condensers Cs and C9 are blocking condensers. H4 and H5 are radio frequency choke coils. Condenser C is a neutralizing condenser for neutralizing radio frequency feedback from the plate circuit to the grid circuit of tube V3. Condensers C11, C12, and coil L3 constitute the output plate circuit of V3 and serve to match the radio frequency load impedance of the tube to the input impedance of phase adjusting network 3. The bias voltage, radio frequency excitation voltage, plate voltage and radio frequency load impedance of tube V3 are adjusted for high efiiciency, high power output condition, since this stage operates as an unmodulated carrier amplifier and can be considered comparable to the output amplifier stage of a radio telegraph transmitter.

In element 3, coil L4 and condenser C13 serve as a radio frequency phase shift network which is adjusted so that the total radio frequency phase shift between amplifier V2 and antenna 4 is correct with respect to the radio frequency phase shift between balanced modulators 5 and 6 and antennas 9 and I0; that is, so that there is a phase difference of 90 electrical degrees between the carrier current in antenna 4 and the suppressed carrier currents in side band antennas 9 and i0. Radio frequency carrier output from phase adjusting network 3 is transmitted through a concentric tube transmission line M to the coupling network, consisting of condensers C14 and C15 and coils L5 and Le, which is installed at the base of antenna 4.

In balanced modulator 5, V4 and V5 are the tubes of a conventional push-pull audio amplifier stage whose grids are coupled to phase shift network I I through input transformer T1 and whose plates are coupled to the plate circuit of balanced modulator tubes V6 and V2 through output transformer T2. A4 and A5 are the filament current sources of the audio amplifier and the balanced modulator tubes respectively G3 and B5 are the grid bias and plate voltage sources respectively of the audio amplifier stage. The balanced modulators consist of two radio frequency amplifier tubes V6 and V7 whose grids receive radio frequency excitation voltage from element I through blocking condensers C16 and C17. The connection is such that radio frequency voltage on the grid of Va is 180 electrical degrees out of phase with that of the grid of V2. H8 and H9 are radio frequency choke coils and R2 and-Rs are grid leak resistors for the grids of V6 and V1.

The plates of V6 and V1 are connected through blocking condensers C18 and C19 to the tuned circuit consisting of coil L2 and condenser C20. This connection effectively places the two plates in parallel to radio frequency voltage. There is no direct current source in the plate circuit of V6 and V7, but the plates are connected through radio frequency chokes H6 and H2 in a push-pull or opposed sense to the output transformer T2 of the audio frequency amplifier stage. Hence the plate circuit of the balanced modulator tubes is inactive except when audio modulation voltage is applied and only one of the tubes Ve-V7 passes plate current at any given instant. For example, V6 would be active during the positive half of the audio frequency cycle and V 1 during the negative half. The result is that the output circuit Car-L1 receives only the two side band frequencies corresponding to the sum and difference of the carrier frequency and the audio frequency, and that the carrier frequency is suppressed.

Element 1 is a conventional class B linear radio frequency amplifier including Vs the function of which is to amplify the double side band output of balanced modulator 5 to the power level required in antennas l0. A6 is the filament current source, Be the plate potential source, and G4 the grid bias source for this amplifier stage. Grid bias voltage is so adjusted as to produce essentially zero plate current in the absence of radio frequency excitation in accordance with conventional practice for linear amplifier stages. H10 and H11 are radio frequency chokes, C21 and C22 are blocking condensers, and C23 is the neutralizing condenser for this stage. Condensers C24 and C25 and coil L8 constitute the radio frequency output circuit for this stage and function to match the plate load impedance to the impedance of the concentric tube transmission line l5 following. Condensers C26, C27 and C28 and coils L9 and L10 constitute the coupling network between the bases of antennas 9 for coupling the transmission line to this antenna circuit.

It is seen that elements 8 and 8 are identical with elements 5 and 1 respectively and serve to supply the required side band current to antennas N in the same fashion. For convenience, therefore, I have shown primed reference characters in elements 6 and 8 to. indicate corresponding parts. The radio frequency excitation to balanced modulator element 6 is the same as that supplied to element 5. The audio frequency voltages to these two elements, however, are supplied by two different audio phase shift network II and [2. The input circuits of these two networks are connected in parallel to a source of audio frequency voltage such as the program line l3, or the output of a microphone or microphone amplifier. These networks are designed so that the difference in the phase shift through the networks is substantially ninety electrical degrees throughout the useful audio frequency range. In network H, for example, the coils and condenser are constructed to have reasonably small losses, so that the attenuation is negligible when the network is terminated in its characteristic impedance. Resistor Rs, connected across the input winding of transformer T1, is of such value that the effective parallel impedance of said resistor and transformer provides the proper termination for network ll. 7 a

The outlet of amplifier 8 is conducted through concentric tube transmission line I6 and applied to antennas I0 through a coupling network, including coils Liz and L14 and condensers C39, C40 and C41, which is similar to that in connection with antennas 9.

Fig. 6 shows the characteristics of a sample design of audio frequency phase shifting network. The deviation in phase difference from degrees is seen to be within plus or minus 15 degrees over the frequency range of 65 to 10,000 0. p. s. The following considerations will show the effect of small deviations from the required phase shift of 90 degrees.

Returning to Equation 2, the total field intensity is proportional to cos -wt[1+m{cos 0 cos t-l-sin 0 sin tn] where (p is the phase deviation in degrees. The term: mEcos 0 cos t+sin 0 sin (pt-( H for any particular value of 0 has two conventional vector components. They are displaced in phase by an angle 1r/2+ Consider the case when is 45 degrees. At this point the vectors are equal in length. Their sum, .707m (1/ Qf+]./90+(p) is the percentage of modulation existing at an angle of 45 degrees with the meridian. At an angle of 135 degrees the sum becomes (-l/0+1/90+ (.707m) and so on. These values or" 0 are used for illustrative purposes because the percentage of modulation is most sensitive to phase deviations in these directions. The following table shows the change in percent modulation in decibels as a function of the phase deviation in degrees for the most sensitive directions:

Phase deviation "The table shows that the system is not particularly critical as to audio phase balance, as a deviation as much as plus or minus 20 degrees only produces a maximum variation of 3 decibels in the frequency response, and this only occurs at the diagonal angles. It is, of course, clear that in the north and south, and east and west directions, no change in the transmitted frequency response occurs. This simple requirement, of course, means that a satisfactory polyphase audio source can readily be set up.

' Fig. 7 shows an alternative to the antenna system shown in Fig. 5, in which the carrier antenna i has been eliminated. The coils and condensers in the coupling Cil'Clll'JS oi 7 are identical to and numbered to correspond with those of Fig. 5. Condenser (315 of the carrier coupling circuit instead of being connected to a separate carrier antenna is connected to center taps on coils L10 and L14 of the side band coupling circuits. The result is that the carrier current is divided into four portions which flow in the L14 result in a balanced or bridge circuit involving the carrier and the side band circuits, so that there is no coupling between them.

Instead of four or five separate antenna structures as shown in Figs. 5 and 7, a more economical arrangement consists of a central structure for the carrier with the four side band antennas suspended therefrom. That this is entirely feasible is shown from a consideration of the dimensions involved. In the development of Equation 2 it was assumed that the spacing of the directional elements was small in comparison with a wavelength. This small spacing is desirable not only from the point of view of the directional characteristic in the ground plane, but also in order that the distribution of the figureof-8 directional system in the vertical plane (as a function of the vertical angle) be as nearly as possible similar to the vertical distribution of the carrier antenna. Using the ratio of d, the spacing, to A, the wavelength oi one to thirty, consider the following example:

Frequency 1000 KC.

Halfwave antenna 193. feet high Spacing of elements -1 32.8 feet 5 It would hardly be out of line to assume that the side band antenna systems could be suspended from the center carrier antenna structure, without greatly increasing the cost of the antenna system. Electrical desirability and mechanical convenience are fortunately concurrent.

Practical aspects of the system Carrier amplifier Carrier power Each side band amplifier carrier power This should be contrasted with the conventional system which requires that the final amplifier be capable of supplying four times carrier.

3. The class C telegraph operation of the carrier amplifier reduces the hum problem to a minimum.

4. The minimum audio frequency load on the filter system is four times the lowest desired audio frequency.

5. Slight maladjustment of the system does not seriously impair fidelity.

6. High overall operating efficiency is realized for the complete transmitter.

The following is an example of the ecenomy of the polyphase system as applied to a proposed kw. transmitter. This transmitter would utilize four water-cooled vacuum tubes, two of which are in the carrier amplifier and one in each of the side band amplifiers. These tubes would be driven by six type 849A vacuum tubes, two for the carrier amplifier and two modulators for each of the side band amplifiers. These tubes in turn can be driven from a single source of radio frequency voltage and a pair of 803 vacuum tubes would provide sufiicient power for driving purposes. The following table outlines the probable power consumption and tube expense of this transmitter:

50 low. transmitter Plate input, carrier 72 kw, Plate voltage 18 kv. Plate current 4.0 amp. Plate current per tube 2.0 amp. Peak current per tube 6.6 amp. Plate current each side band amplifier at modulation 1.27 amp. Plate current each side band amplifier at 30% modulation .382 amp. Plate input, two side band amplifiers at 30% modulation 13.75 kw. Filament power 4 tubes, 61 ampere at 22 V 5.37 kw. Plate input carrier amplifier 72.0 kw. Plate input side band amplifiers 13.75 kw.

91.12 kw. Allow 20 kw. for exciter and amplifiers 20.00

Total 111.12 kw.

To further emphasize the importance of the system as applied to high power broadcasting,

owing data have been compiled concernossible layout for a 500 kw. transmitter. 'ansmitter would utilize four type 898 tubes in the carrier amplifier and two of the side band amplifiers. The magof the saving is such as to shed possibly ight on the economies of 500 kw. opera- 500 kw. transmitter nput carrier amplifier 720.0 kw. input side band amplifiers 137.5 kw. it power, 8 tubes, 207A at 38 54.7 kw. and auxiliaries 150.0 kw.

.otal 1062.2 kw.

ever in the drawings and specification I ferred to specific elements, such as batirces of power and bias potential, particuse controlling circuits and the like; I have d such devices to be illustrative only and :mploy in lieu thereof any suitable means in the art or as yet undisclosed. It is to arstood that where batteries are shown .ernating current, or rectified alternating may be employed as in conventional sysystem of my invention is particularly apto commercial broadcasting of high powise of the great savings in initial cost, op-

and maintenance effected, especially in the long hours of operation daily. As a of the savings accomplished by the sysmy invention, I cite the following:

500 kw. transmitter 300 kw. at $.008 for 19 hours=$4=5.50 per day, 365 days per year=$16,500 per year. 12 tubes eliminated-life, 10,000 hours,

aving: $16,500+13,350=$29,850 per year.

50 kw. transmitter 60 kw. at 1.2 for 19 hours/days=$13.68

per day :65 X $13.68=$5,000 per year.

=$13,350 per year ibes at $425.00life 6500 hours against 2 ibes $1600.00-life 10,000 hours IGOOX 19 65 W- =$2,210 per year 110$1,810=$300 I+$300=$5,300.00 total annual savin =$1,81O per year of modulation to azimuth angle is adaptable also to a variety of applications where such relation may be useful, such as radio compass systems, synchronizing systems, duplex signal transmission, and other fields as will be apparent to those skilled in the art. Thus. I desire it understood that no limitatioi'is upon my invention are intended except as may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A high frequency Signalling transmission system comprising means for broadcasting unmodulated carrier energ directional means for propar gatin modulation band signal energy of the type covering simultaneously a band of frequencies, and means for timing the energization of said directional neans according to the frequency of said modulation side band signal energy for effecting radial; n, the phase of which is a function of the azimuth angle.

2. A high frequency signalling transmission system compr' g means for broadcasting unmodulated carrier energy, directional means for propagating polyphase modulation side band signal energy of the type covering simultaneously a band of frequencies, and means for timing the energize.- tion of said directional means according to the frequency of said modulation side band signal energy for effecting radiation, the phase of the composite field of said modulation side band signal energy being a function of the azimuth angle.

3. A high frequency signaling transmission system comprisin separate means for propagating radio frequency carrier energy and modulation side band radio frequency energy of the type covering simultaneously a band of frequencies, means for timing the radiation of the modulation side band signal energy according to the frequency of the modulation side ban-d signal ener y, and means for controlling the space phase of the composite field intensity produced by said separate means so that the roct-mean-square radio frequency power output of said separate means is constant throughout the modulation cycle.

4;. A high frequency signalling transmission system comprising separate means for propagating carrier energy and modulation side band signal energy of the type covering simultaneously a band of frequencies, the output of said means for propagating carrier energy being substantially constant, and means for controlling the phase of the modulation side band signal energy as a function of the azimuth angle at a rate dependent upon the frequency of the modulation side band signal energy so that the root-mean-square output of said means for propagating modulation side band signal energy is constant throughout the modulation cycle.

5. A high frequency signalling transmission system comprising nondirectional radiating means and means for individually supplying carrier energy thereto, polyphase directional radiating means and means for supplying polyphase modulation side band signal energy of the type covering simultaneously a band of frequencies thereto at a rate dependent upon the frequency of the modulation side band signal energy, the phase of the modulation in the composite field intensity being a function of the azimuth angle.

6. A high frequency signalling transmission system comprising nondirecticnal radiatin means and means for individually supplying carrier energy thereto for establishing a uniform field of carrier energy about said radiating means, multiple radiating means within said field and means for supplying modulation side band signal energy of the type covering simultaneously a band of frequencies thereto for establishing separate-restricted fields of modulation side band signal energy superimposed on said field of carrier energy at a rate dependent upon the frequency of the modulation side band signal energy, the phase of the modulation side band signal energy in the respective restricted fields beinga function of the azimuth angle.

7. The method of high frequency transmission which consists in establishing in space separate fields of carrier energy and modulation side band signal energy of the type covering simultaneously a band of frequencies, controlling the transmission of the modulation side band signal energy in proportion to the frequency of the modulation side band signal energy and varying the phase of the modulation in the composite field as a function of the azimuth angle.

8. The method of high frequency transmission which consists in establishing a composite field of carrier energy and modulation side band signal energy of the type covering simultaneously a band of frequencies in space, and separately controlling the phase of the modulation as a function of the azimuth angle at a rate dependent upon the frequency of the modulation side band signal energy.

9. The method of broadcastin high frequency signal energy which consists in establishing in space a field of high frequency energy of substantially constant power input modulating said field by a signal of the type covering simultaneously a band of frequencies, controlling the phase of the maximum intensity of said field as a function of the azimuth angle at a rate proportional to the modulating frequency, and varying the intensity of said field in accordance with the modulating signal.

10. The method of broadcasting high frequency signal energy which consists in uniformly propagating in all directions in the ground plane an amplitude modulated signal wave of the type covering simultaneously a band of frequencies and having uniform amplitude of modulation in all directions and controlling the rate of propagation according to the frequency of modulation of the modulated signal wave with the phase of the modulation varying as a function of the azimuth angle.

11. The method of high frequency signalling which includes transmitting high frequency amplitude modulated signal waves or" the type covering simultaneously a band of frequencies along different azimuths and controlling the space phase of the amplitude modulated signal waves as a function of the azimuth angle at a rate dependent upon the modulation frequency of the amplitude modulated signal waves.

12. The method of broadcasting high frequency signal energy with substantially constant power consumption throughout the modulation cycle which consists in broadcasting an ampliti; modulated signal wave of the type covering sirm taneously a band of frequencies, and controlli the space phase of the modulation energy as function of the azimuth angle so that instant neous field intensities are 180 out of phase points of 180 displacement in the ground plai power maxima in one phase being accompanied power minima in th opposite phase to preser constancy in the power input throughout the mo ulation cycle at a rate dependent upon the mod lation frequency of the amplitude modulated si nal wave.

14. A high frequency signalling transmissii system comprising a source of unmodulated ca rier energy, Separate sources of polyphase mod lation side band signal energy of the type cove which includes controlling the space phase of an amplitude modulated signal wave of the type covering simultaneously a band of frequencies as a function of the azimuth angle so that instantaneous field intensities at points of 180 displacement in the ground plane are 180 out of phase at a rate dependent upon the modulation frequency of the amplitude modulated signal wave.

13. The method of broadcasting high frequency signal energy with substantially constant power consumption throughout the modulation cycle 5 ing simultaneously a band of frequencies, and 2 antenna system including radiators coupled wir each phase of said polyphase modulation sign energy and mounted relative to each other abo' a central point in accordance with the phase the signal energy to be radiated therefrom, sa antenna system including means separately cox nected with the first said source for independent radiating said unmodulated carrier energy.

15. A high frequency signalling transmissic system as set forth in claim 14 and wherein tl last said means comprises a nondirectional r2 diator disposed at the central point in said systei and separately coupled with said source of ur modulated carrier energy.

16. A high frequency signalling transmissio system as set forth in claim 14 and wherein tl'. last said means comprises a balanced circuit in terconnecting the said radiators and said sourc of carrier energy for radiating unmodulated car rier energy from said radiators, said balance 40 circuit operating to annul coupling between th separate radiators and the polyphase signal en ergy supplied thereto.

17. A high frequency signalling transmissio system comprising a source of unmodulated car rier energy, a. source of modulation signal energ of the type covering simultaneously a band c frequencies, phase splitting means coupled witi said source of signal energy, separate means fo modulating carrier energy from said source there of by each phase of said signal energy, means f0 suppressing the carrier energy in each phase 0 the signal modulated energy, means for separatelj and independently radiating unmodulated carrie energy derived from said source thereof and eac] phase of the signal modulated energy, the radiat ing means for each phase of said signal modulate energy being disposed relative to each other abou a central point in accordance with the phase 0 the energy to be radiated therefrom and mean for controlling the rate of radiation of each phasi of the signal modulated energy according to th frequency of said source of modulation signa energy.

18. A high frequency signalling transmissioi system comprising a source of unmodulated car rier energy, a source of modulation signal energ: of the type covering simultaneously a band 0; frequencies, phase splitting means coupled witl said source of signal energy, separate modulating means coupled with said source of carrier energ and each phase of said phase splitting means anc operative to produce suppressed carrier polyphase double side band signal modulated energy, mean: for radiating unmodulated carrier energy derivec' from said source of carrier energy, and separate liating each phase of said polyphase .ted energy at a rate dependent upon of said modulating means, the rafor each phase of said signal moduieing disposed in space in accordance se relations of the energy to be rarom.

frequency signalling transmission fisin'g a source of unmodulated carsource of modulation signal energy Vering simultaneously a band of freseparate circuits coupled with the co, phase shifting means in at least ircuits to produce signal currents in iture in the separate circuits, balatcr means in each of said circuits said source of carrier energy and aliver double side band signal moduwith carrier energy suppressed, said and signal modulated energy being tdraturein the separate modulator is for separately and independently imodulated carrier energy derived irce thereof and each phase of said band signal modulated energy, the :ans for each phase of said signal 1ergy being disposed in quadrature qace, and means for controlling the ion of each phase of the signal moduaccording to the frequency of said dulation signal energy. :thod of broadcasting high frequency includes directively and successively .n space an amplitude modulated sigthe type covering simultaneously a quencies, maintaining the percent hereof the same in all directions, and phase of the modulation with direcproportional to the modulation he s amplitude modulated signal wave. idcasting system comprising nonneans for radiating unmodulated gy characterized by the function tonal means for radiating suppressed 1 energy of the type covering simuland of frequencies characterized by sin mi cos t, other directional means pace in 90 relation to the first said leans for radiating suppressed carrier :y characterized by the function where w represents the carrier frep the signal frequency, and means for controllin the radiation of the suppressed carrier signal in proportion to the value of p.

22. A broadcasting system comprising nondirectional means for radiating unmodulated carrier energy, multiple directional means for radiating polyphase suppressed carrier signal energy of the type cove *ing simultaneously a band of frequencies, with the radiating components of said multiple directional means disposed in space in relation to the polyphase energy radiated thereby for producing in cooperation with said nondirectional means a composite field characterized by the function cos t-0), where p represents the signal frequency and 6 the azimuth angle, and means for controlling the radiation of the suppressed carrier signal in. proportion to the value Of p.

23. An antenna modulation system including means for generating carrier frequency current, a source of modulation current of the characteristics required for the transmission of signals covering simultaneously a hand. of frequencies, means for applying one of said currents to create an omni-directional field, and means for applying the other of said currents to create a field rotating at the frequencies of said band of frequencies.

24. An antenna modulation system including means for generating carrier frequency currents, a source of modulation currents of the characteristics required for the transmission of signals covering simultaneously a band of frequencies, means for applying one of said currents to create an omni-directional field, and means for applying the other of said currents to create a field rotating at the frequency 01' the said other currents.

25. An antenna modulation system including means for generating a carrier frequency current, a source of modulation currents of the characteristics required for the simultaneous transmission of signals covering simultaneously a band of frequencies. means for applying one of. said currents to create an omnidirectional field, and means for applying the other of sai currents to create a field in which components rotate at the frequencies corresponding to the frequencies of said modulation.

26. The method of transmitting simultaneously a wide range of modulation frequencies which includes radiating an unmodulated carrier wave, establishing a rotating field, and varying the rate of rotation of said field as a function of said modulation frequencies.

J OHN F. BYRNE. 

